Originally Posted by
RatherBeFlying
I once discovered a dead airspeed on takeoff and took it into the air to avoid trundling into the ravine at the end of the runway. I spent half an hour sorting out what to do. Pretty simple in a 172 on a nice day. Much more difficult in a jet.
Indeed but that's easy - you know of the problem while still on the ground. I'm sure we've all flown circuits in light aircraft with the ASI covered over.
This would have been more subtle - airspeed indications would have been OK up until the point where the pitots froze. If the autopilot was engaged when that happened, that may have caused confusion as well (presumably they were in IMC).